The present disclosure relates to a gas turbine engine and, more particularly, to a fuel injector system therefor and method of operation thereof.
Gas turbine engines, such as those that power modern commercial and military aircraft, include a compressor section to pressurize a supply of air, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases and generate thrust.
The combustor section generally includes a multiple of circumferentially distributed fuel injectors that axially project into a combustion chamber to supply fuel to be mixed with the pressurized air. Gas turbine engines typically include multiple individually controlled centralized staging valves with multiple fuel supply manifolds that deliver fuel to the fuel injectors. There is one fuel supply manifold for each stage, thus, each fuel injector may have multiple fuel supply connections, one for each stage.
Each fuel injector typically has an inlet fitting connected to the manifold at the base, a strut or stem connected to the base fitting, and a nozzle tip assembly connected to the strut or stem to spray the fuel into the combustion chamber. A fuel conduit extends through the strut to supply the fuel from the inlet fitting to the nozzle tip assembly. Appropriate valves and/or flow dividers are provided to direct and control the flow of fuel through the nozzle assembly.
The nozzle assembly often includes pilot and main nozzles. Generally, the main nozzles are for normal and high power situations, while the pilot nozzles are used for start operation. The nozzles have relatively small orifices and fuel conduits in the strut which may be prone to coke formation. Coke formation may result in narrowed fuel orifices, uneven fuel burn and increased maintenance requirements.
Conventional fuel injector designs typically utilize a heat shield around the fuel injector strut to provide an insulated air gap and reduce the heat transfer rate within the diffuser case module to the fuel.